1.A preliminary screening of potentially antimalarial plants against Plasmodium falciparum in vitro
Khaw, L.T. ; Leerach ; N., Yap ; N.J. ; Jaturas ; N. ; Mahboob T. ; Tan, T.C. ; Lim, Y.A.L.
Tropical Biomedicine 2015;32(4):676-683
Plasmodium is a blood protozoan parasite that is responsible for malaria. To date,
Plasmodium falciparum has shown multi-drug resistance, particularly in Thailand, Myanmar
and Malaysia. The aim of the study is to screen the plant extracts that can effectively inhibit
P. falciparum 3D7, a common lab strain malaria parasite. Nine plants were collected and
processed through maceration using hexane, chloroform and ethanol, resulting in 24 crude
plant extracts. Of these, extracts from Artabotrys crassifolius, Pericampylus glacus and
Leuconotis eugeniifolia showed promising antiplasmodial activities at IC50 of 15.32 to 39.75
μg/mL in a modified schizont maturation assay. Further studies are warranted to explore its
efficacies and lead compounds of these three plant extracts for the development of
antiplasmodial drugs.
2.Toxoplasmosis in HIV and non HIV prisoners in Malaysia
Angal, L., Lim, Y.A., Yap, N.J., Ngui, R., Amir, A., Rohela, M.
Tropical Biomedicine 2016;33(1):159-169
This is the first Malaysian study to determine the trend and risk factors of Toxoplasma
gondii infection in HIV and non-HIV among prisoners in terms of socio-demographic and
behavioural characteristics, clinical presentations and haematological distributions. Blood
samples from 303 participants, comprising 133 HIV positive and 170 HIV negative inmates
were collected in EDTA and plain tubes. Two mls of each blood sample in plain tubes were
centrifuged at 1500 rpm for 10 minutes and the sera obtained were subjected to ELISA for
detection of Toxoplasma IgM and IgG antibody towards Toxoplasma antigen. Seropositive
samples for Toxoplasma IgM or both Toxoplasma IgM and IgG were further tested with
Novalisa Toxoplasma gondii IgG avidity test to rule out acute from latent infections. Blood
in EDTA tubes were sent to Clinical Diagnostic Lab (CDL), University Malaya Medical Centre
(UMMC), Kuala Lumpur for complete blood count and differential count analysis. Overall
seroprevalence of anti-T. gondii antibodies was detected in 41.9% (127 out of 303) of the
participants. Anti-T. gondii antibodies was detected in 63.2% (84 out of 133) of HIV positive
subjects and in 25.3% (43 out of 170) of HIV negative subjects. Seroprevalence of anti-T.
gondii antibodies was significantly higher in HIV positive than in HIV negative subjects (OR
= 5.06; 95% CI = 3.09-8.30; p < 0.001). The rate of T. gondii seropositivity increased significantly
in those aged 40 years and above, HIV positive individuals and those with history of drug
abuse. White blood cells (WBCs), neutrophils and basophils counts decreased significantly in
those infected with Toxoplasma. Creating awareness about T. gondii infection and follow-up
of their status is recommended. Moreover, screening of T. gondii infection in HIV-infected
individuals should be considered for better treatment and management, including control and
prevention.
3.Imported case of Leishmania tropica cutaneous leishmaniasis in a 10-year-old child in Malaysia
Tan, T.K. ; Yap, N.J. ; Leong, K.F. ; Teh, C.S. ; Tay, S.T. ; Lim, Y.A.L.
Tropical Biomedicine 2022;39(No.1):86-88
The present paper reported a first imported case of cutaneous leishmaniasis in a 10-yearold child who returned from Saudi Arabia to Malaysia. Six weeks after his travel to Malaysia,
two erythematous dermal nodules were developed over his right cheek and chin. Occurrence
of intracellular amastigote of Leishmania was observed through examination of skin biopsy
with hematoxylin and eosin stain. Furthermore, molecular analysis of ribosomal internal
transcribed spacer 1 (ITS1) of Leishmania spp. confirmed the child was infected with Leishmania
tropica. The child was given oral fluconazole and he had a 80% recovery before he went back
to Saudi Arabia.
4.Genetic diversity of Merozoite Surface Protein-1 gene block 2 allelic types in Plasmodium falciparum isolates from Malaysia and Thailand
Goh, X.T. ; Chua, K.H. ; Vythilingam, I. ; Lee, P.C. ; Tan, T.C. ; Yap, N.J. ; Chai, H.C. ; Nissapatorn, V. ; Lim, Y.A.L
Tropical Biomedicine 2019;36(1):70-80
Malaria is the most common vector-borne parasitic disease in Malaysia and Thailand,
especially in Malayan Borneo and along the Thailand border areas, but little is known about
the genetic diversity of the parasite. Present study aims to investigate the genetic diversity
of Plasmodium falciparum isolates in these two countries and eventually contributes to
more effective malaria control strategies, particularly in vaccine and antimalarial treatment.
One hundred and seventy three P. falciparum isolates were collected from Malaysia (n = 67)
and Thailand (n = 106) and genotyped using nested PCR targeting the polymorphic region of
MSP-1, block 2. Sequence analysis was conducted to investigate the allele diversity of the
isolates. Three allelic families were identified in Malaysian and Thailand P. falciparum
isolates, MAD20, K1 and RO33. Sequence analysis revealed that there were 5 different
MAD20, 1 K1 and 2 different RO33 for Malaysian isolates. Thailand isolates exhibited greater
polymorphism because there were 13 different MAD20, 6 different K1 and 2 different RO33
identified in this study. Multiclonal infections were observed for the isolates in both countries,
however, low multiplicity of infection (MOI) was observed for Malaysian (1.1) and Thailand
(1.2) isolates. Phylogenetic analysis showed that P. falciparum isolates of Malaysia and
Thailand were clustered in the same group for all the allelic families. Population structure of
P. falciparum isolates in Malaysia and Thailand exhibit extensive genetic polymorphism but
showed high similarities as well as comparable MOI.